Method of transmitting feedback information using an extended subheader

ABSTRACT

A method of transmitting feedback information is disclosed. More specifically, a mobile station (MS) receives a Protocol Data Unit (PDU) which includes a Medium Access Channel (MAC) header from a base station (BS). Thereafter, the MS determines from the received MAC header whether an extended subheader group appears after the MAC header, and also identifies a feedback request extended subheader from the extended subheader group. Lastly, the MS transmits the feedback information according to the feedback request extended subheader.

This application claims the benefit of earlier filing date and right ofpriority to Korean Application No. 10-2004-112927, filed on Dec. 27,2004, Korean Application No. 10-2005-000930, filed on Jan. 5, 2005, andU.S. Provisional Application No. 60/663,347 filed on Mar. 17, 2005,which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of transmitting feedbackinformation, and more particularly, to a method of transmitting feedbackinformation using an extended subheader.

2. Discussion of the Related Art

FIG. 1 is an example illustrating a structure of a Medium Access Control(MAC) Protocol Data Unit (PDU). As illustrated in FIG. 1, the MACManagement PDU includes a MAC Header 11, a Management Message Type 12,and a MAC Management Payload 13. Furthermore, a Bandwidth Request PDU isused by each user to dynamically request a necessary bandwidth fortransmitting uplink data. The Bandwidth Request PDU is special in thatit only includes the bandwidth request header and nothing else includinga payload.

FIG. 2 illustrates a structure of the MAC PDU of FIG. 1. Morespecifically, if a MAC PDU is formed without packing or fragmenting aMAC Service Data Unit (SDU), as illustrated in FIG. 2, a MAC PDU doesnot included a packing subheader or a fragmentation subheader.

FIG. 3 illustrates another example of a structure of a MAC PDU. Asillustrated in FIG. 3, a MAC SDU 31 is fragmented to be included informing two or more MAC PDUs 30 a and 30 b. In forming the MAC PDUs 30 aand 30 b, fragmentation subheaders 34 a and 34 b are attached behind theMAC headers 33 a and 33 b, respectively. Moreover, MAC SDUs 35 a and 35b are attached behind the fragmentation subheaders 34 a and 34 b,respectively, to form MAC PDUs 30 a and 30 b.

FIG. 4 is yet another example illustrating a structure of a MAC PDU. InFIG. 4, a MAC PDU is formed by packing two or more MAC SDUs (e.g., MACSDU #1 41 a and MAC SDU #2 41 b). These MAC SDUs 44 and 46 are attachedbehind packing subheaders 43 and 46, respectively. Here, the MAC PDU hasa MAC header 42 in front and more specifically, in front of the packingsubheader 43.

As described above, when the MAC SDU is fragmented or packed,fragmentation subheader or packing subheader is attached to therespective MAC PDU(s). As such, the MAC PDU can be classified in itsrespective units and according to frame numbers.

In the conventional art, only the methods related to fragmenting andpacking are available. In other words, the conventional art does notinclude a MAC PDU structure having various expanded subheaders.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a method oftransmitting feedback information using an extended subheader thatsubstantially obviates one or more problems due to limitations anddisadvantages of the related art.

An object of the present invention is to provide a method oftransmitting feedback information.

Another object of the present invention is to provide a method ofreceiving feedback information.

A further object of the present invention is to provide a system fortransmitting and receiving feedback information.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, amethod of transmitting feedback information includes a mobile station(MS) which receives from a base station (BS) a Protocol Data Unit (PDU)which includes a Medium Access Channel (MAC) header. Thereafter, the MSdetermines from the received MAC header whether an extended subheadergroup appears after the MAC header, and also identifies a feedbackrequest extended subheader from the extended subheader group. Lastly,the MS transmits the feedback information according to the feedbackrequest extended subheader.

In another aspect of the present invention, a method of transmittingfeedback information includes a base station (BS) which transmits aProtocol Data Unit (PDU) which includes a Medium Access Channel (MAC)header which indicates an existence of an extended subheader group.Here, the extended subheader group includes a feedback request extendedsubheader. Thereafter, the BS receives the feedback informationtransmitted from a mobile station (MS).

Yet in another aspect of the present invention, a system fortransmitting and receiving feedback information includes a base station(BS) which transmits a Protocol Data Unit (PDU) which includes a MediumAccess Channel (MAC) header which indicates whether an extendedsubheader group appears after the MAC header. Here, the extendedsubheader group indicates a feedback request extended subheader. Thesystem also includes a mobile station (MS) which receives the PDU andthen determines from the MAC header whether the extended subheaderappears after the MAC header. Thereafter, the MS determines from the MACheader whether an extended subheader group appears after the MAC header.Moreover, the MS identifies a feedback request extended subheader fromthe extended subheader group. Lastly, the MS transmits the feedbackinformation according to the feedback request extended subheader.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings;

FIG. 1 s an example illustrating a structure of a Medium Access Control(MAC) Protocol Data Unit (PDU);

FIG. 2 illustrates a structure of the MAC PDU of FIG. 1;

FIG. 3 illustrates another example of a structure of a MAC PDU;

FIG. 4 is yet another example illustrating a structure of a MAC PDU;

FIG. 5 illustrates an example of a MAC header;

FIG. 6 is another example illustrating a MAC header;

FIG. 7 depicts an example of a MAC PDU;

FIG. 8 is a diagram depicting a structure of an extended subheadergroup; and

FIG. 9 is an example of an Extended Subheader Format (ESF).

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

FIG. 5 illustrates an example of a MAC header. As illustrated in FIG. 5,the MAC header includes a ‘type’ field represented by 6 bits. Moreover,the ‘type’ field can express six (6) different types of subheadersdepending on the bitmap type. These different types of subheaders can beattached behind the MAC header, and a specific type of the subheader canbe indicated in the ‘type’ field. This type field indicates six (6)types of subheaders, and each subheader has a size of 2 bytes.

Table 1 shows an example of six (6) types of subheaders. TABLE 1 Typebit Value #5 Most Mesh subheader Significant 1 = present, 0 = absent Bit(MSB) #4 ARQ Feedback Payload 1 = present, 0 = absent #3 Extended TypeIndicates whether the present Packing or Fragmentation Subheaders, isExtended 1 = Extended 0 = Not Extended. Applicable to connections whereARQ is not enabled #2 Fragment subheader 1 = present, 0 = absent #1Packing subheader 1 = present, 0 = absent #0 Least Downlink:FAST-FEEDBACK Allocation subheader Significant Uplink: Grant Managementsubheader Bit (LSB) 1 = present, 0 = absent

As shown in Table 1, there are six types of subheaders, represented by amost significant bit (MSB) #5 to a least significant bit (LSB) #0. Eachtype of subheader can be indicated as being present or as being absent.More specifically, the type bit of ‘1’ or ‘0’ indicates presence orabsence of the particular subheader, respectively.

For example, if the ‘type’bit #5 is indicated as ‘1,’ the MAC PDUincludes a mesh subheader. That is, in a mesh mode, each mobile station(MS) is given a Node identification (Node ID) so that each MS can beidentified. To this end, the mesh subheader can be used to provide NodeID to each MS. If the ‘type’ bit #4 is indicated as 1, then the MAC PDUincludes a subheader for an Automatic Repeat Request (ARQ). If the‘type’ bit #3 is indicated as 1, then the MAC PDU includes an extendedpacking subheader or an extended fragmentation subheader. If the ‘type’bit #2 and the ‘type’ bit #1 are each indicated as ‘1,’ a packet PDUcorresponding to a user are mapped to a MAC SDU payload. Moreover, a MACPDU is formed by having a MAC header and a Cyclic Redundancy Check (CRC)attached thereto.

Lastly, an application of the bit of the ‘type’ bit #0 is different foran uplink transmission and for a downlink transmission. If the ‘type’bit #0 is indicated as ‘1,’ the MAC PDU includes a fast-feedbackallocation subheader. Here, the fast-feedback allocation subheader ispositioned at the end of all subheaders. In order to receive a feedbackvalue from the MS, the fast-feedback allocation subheader is used toallocate resource(s) in a fast feedback channel (e.g., Channel QualityIndication Channel) and the type of feedback information.

An example of a fast-feedback allocation subheader is presented in Table2. TABLE 2 Syntax Size Notes FAST-FEEDBACK allocation Subheader {Allocation offset 6 bits Feedback type 2 bits 00: Fast DL measurement01: Fast MIMO feedback antenna#0 10: Fast MIMO feedback antenna#1 11:MIMO mode permutation mode feedback }

As depicted in Table 2, the fast-feedback allocation subheader uses an‘allocation offset’ to allocate a Channel Quality Indication Channel(CQICH), which is indicated by a fast feedback channel InformationElement (IE), for transmitting feedback information. Here, theallocation of CQICH can be represented in slots. In addition, a type offeedback information can be selected via the ‘feedback type.’ After theMS receives the fast-feedback allocation subheader, the MS can use thefeedback value to request for a change to a Multi Input Multi Output(MIMO) mode or to a permutation mode.

For an uplink, if the ‘type’ bit #0 is indicated as ‘1,’ the MAC PDUincludes a Grant Management subheader. The Grant Management subheader isused to deliver information related to managing the uplink resources.Moreover, the use of the Grant Management subheader can vary dependingon a subheader type. Based on the type of service, an allocation requestfor bandwidth using a piggyback request, bandwidth stealing scheme, anda polling scheme.

As illustrated in FIG. 5, the MAC header includes two reserved bits,each having 1 bit length. Here, any one of the two reserved bits can beused to include information of an enhanced fast-feedback allocationsubheader. In other words, a reserved bit can be used to indicatewhether an enhanced fast-feedback allocation subheader is attached.

If the reserved bit is indicated as l, the MAC header includesinformation of existence of the enhanced fast-feedback allocationsubheader, and alternatively, if the reserved bit is indicated as ‘0,’the MAC header does not include any information on the enhancedfast-feedback allocation subheader.

Table 3 shows an example of an enhanced fast-feedback allocationsubheader. TABLE 3 Size Syntax (bits) Notes Enhanced Fast-feedbackallocation subheader{ Allocation type 1 0 = Use Fast-Feedback channel 1= Use Feedback MAC header If allocation type == 0 { Allocation offset 6Represented in slots, starting frame offset value for Fast-Feedbackchannel CQICH_num 4 Number of CQICH slot(s) to be used Feedback type 3#0 least significant bit(LSB) ? Fast DL measurement #1 - Fast MIMOfeedback, antenna #0 #2 - Fast MIMO feedback, antenna #1 #3 - Fast MIMOfeedback, antenna #2 #4 - Fast MIMO feedback, antenna #3 #5 - MIMO modeand Permutation mode feedback #6-#8 reserved Frame offset 2 BS indicatesstarting frame } else { UIUC 4 Duration 4 MS indicates starting frameFeedback type 4 Refer to Table 4 Frame offset 3 }

According to Table 3, the enhanced fast-feedback allocation subheadertransmits a data packet to the MS. In addition, the enhancedfast-feedback allocation subheader requests for feedback on informationpertaining to the transmission channel and weight value(s) of theantennas. Here, additional information can be requested such as a methodof transmitting the feedback information.

In Table 3, an ‘allocation type’ field can be used to select a method oftransmitting feedback information. For example, if the ‘allocation type’field is indicated by ‘0,’ the MS uses the fast feedback channel totransmit the feedback information. In such a case, an ‘allocationoffset’ field is used to indicate the location of the fast feedbackchannel, and a ‘CQICH_num’ field is used to determine a number of slotsto be used transmit the feedback information.

Moreover, a ‘feedback type’ field is used to indicate the contents ofthe feedback information. For example, if a BS uses two antennas, the BScan request for weight values corresponding to a first antenna and asecond antenna while allocating two slots. Then the MS can send theweight value for the first antenna and the weight value for the secondantenna using the allocated slots.

Furthermore, a ‘frame offset’ field can be used to provide informationas to when the MS should send the feedback information. That is, afterthe MS receives the subheader, the MS can send the feedback informationafter a specified period or after a specified number of frames.

Alternatively, if the ‘allocation type’ field is indicated by ‘1,’ theMS uses the MAC header to transmit the feedback information. Here, a‘duration’ field is used to provided information regarding allocatedwireless resource in the uplink, and a ‘feedback type’ is used toindicate the type of feedback information.

Table 4 is an example illustrating feedback information corresponding to‘feedback type’ field value. TABLE 4 Feedback Type Feedback contentsDescription 0b0000 Set as described in table 296d MIMO mode andpermutation feedback 0b0001 DL average CQI (5 bits) 5 bits CQI feedback0b0010 Number of index L(2 bits) + MIMO coefficients MIMO coefficient (5bits. feedback 8.4.5.4.10.6) 0b0011 Preferred-DIUC(4 bits) Preferred DLchannel DIUC feedback 0b0100 UL-TX-Power(7 bits) UL transmission power0b0101 Preferred DIUC(4 bits) + PHY channel feedback UL-TX-Power(7bits) + UL-headroom(6 bits) 0b0110 Number of bands, N(2 bits) + N CQIsof multiple AMC occurrences of ′band bands index(6 bits) + CQI (5 bits)0b0111 Number of feedback types, Multiple types of 0(2 bits) + Ooccurrences of feedback ‘feedback type(4 bits) + feedback content(variable)’ 0b1000- Reserved for future use 0b1111

As described above, if the ‘allocation type’ field is indicated by ‘1,’the MS receives the enhanced fast-feedback allocation subheader and usesthe allocated uplink wireless resources to transmit the feedbackinformation via the MAC header.

FIG. 6 is another example illustrating a MAC header. As illustrated inFIG. 6, the MAC header includes an Extended Subheader Format (ESF) fieldto further express an extended subheader group. That is, if the ESFfield value is set to ‘1,’ an extended subheader group is providedbetween the MAC header and six types of subheaders (immediately afterthe MAC header), which is expressed via a ‘type’ field. Alternatively,the extended subheader group can appear between the subheaders and apayload. Hereafter, a term ‘extended subheader’ may be usedinterchangeably as a term ‘extended subheader group.’

FIG. 7 depicts an example of a MAC PDU. As show in this figure, the MACPDU includes a MAC header 71, an ESF 72, subheaders 73, a payload 74,and a CRC 75. The ESF 72 can be located between the MAC header 71 andthe subheaders 73, and the length of the ESF 72 can be determined basedon a number of attached subheaders. Alternatively, the ESF 72 can appearor attached behind the subheaders 73.

The BS can set the value of the ESF field as ‘1’ in the MAC header sothat the MS can be notified as to the existence of the ESF between theMAC header and the subheaders. Furthermore, the ESF should not beencrypted; however, the MS can perform the error detection operation byusing the CRC located at the end of the PDU.

FIG. 8 is a diagram depicting a structure of an extended subheadergroup. As depicted in FIG. 8, the extended subheader group consists ofan extended subheader lengths field 81 for providing a total length ofthe extended subheader group, a reserved bit field 82, an extendedsubheader type field 83, and an extended subheader body 84. Preferably,the extended subheader lengths field should be represented in 8 bits,and the total length of the extended subheader is represented in bytes.Here, the total length can be represented by maximum of 2⁷ bytes.Furthermore, there can be up to 128 types of extended subheaders.

Table 5 is an example of an extended subheader types. TABLE 5 ESF Typevalue Name Length (bytes) 0 New Extended subheader_1 1 1 New Extendedsubheader_2 2 Bits 2-127 Reserved

Here, Table 5 illustrates addition of two extended subheaders. That is,based on the extended subheader type field 83, a type corresponding to‘0’ has an extended subheader_(—)1 having a length of one (1) byte whilea type corresponding to ‘1’ has an extended subheader_(—)2 having alength of two (2) bytes. Depending on the type, the extended subheadercan be classified into whether the subheader is for uplink or downlinktransmission. For example, a subheader used in the uplink is formed atthe MS and transmitted to the BS, and if the MS receives this subheader,the MS disregards it.

FIG. 9 is an example of a format of an ESF. Here, refer to FIGS. 7 and 8as well as Table 2. In FIG. 9, the MAC PDU includes the extendedsubheader group, and an extended subheader length field 91 is used toindicate a total length of the subheader(s). In this figure, the totallength of the subheaders is six (6) bytes.

In detail, a new extended subheader_(—)1 includes a reserved bit 92 andan extended subheader type 93. Here, the extended subheader type is ‘0’and has a length equaling 1 byte. Moreover, a body 94 of the extendedsubheader contains information of a subheader represented by type ‘0’and having a length of 1 byte.

Furthermore, a new extended subheader_(—)2 includes a reserved bit 95and an extended subheader type 97. Here, the extended subheader type is‘1’ and has a length of 2 bytes. In a body 97 of the extendedsubheader_(—)2, different from the new extended subheader_(—)1, thereare two subheaders having the length of 2 bytes.

Table 6 is an example of a downlink extended subheader attached to theMAC PDU. TABLE 6 ESF Type value Name Length 0 SDU_SN Extended subheader1 1 DL Sleep control Extended subheader 3 2 Feedback request Extendedsubheader 3 3 PDU SN(short) Extended subheader 1 4 PDU SN(long) Extendedsubheader 2 Bits#5-127 Reserved

As shown in Table 6, at least one subheader is attached to the MAC PDUbefore being transmitted. For example, if the ESF type field indicates avalue of ‘00000010, ’a feedback request extended subheader, having alength of 3 bits, is attached to

Table 7 is another example of an uplink extended subheader groupattached to the MAC PDU. TABLE 7 ESF Type value Name Length 0 MIMO modefeedback Extended subheader 1 1 UL Tx power report Extended subheader 12 Mini-Feedback report Extended subheader 2 3 PDU SN(short) ExtendedExtended 1 subheader 4 PDU SN(long) Extended subheader 2 Bits#5-127Reserved

As shown in Table 7, at least one subheader is attached to the MAC PDUbefore being transmitted. For example, if there is a request for MIMOmode change, a MIMO mode feedback extended subheader is transmittedafter a desired mode is selected.

Table 8 is an example of a feedback request extended subheader formatfrom an uplink extended subheader. TABLE 8 Size Name (bits) DescriptionUIUC 4 Feedback type 4 Refer to Table 4 OFDMA 6 The offset is relevanceto the Allocation Start Symbol offset Time field given in the UL-MAPmessage. Subchannel 6 The lowest index subchannel used for carryingoffset the burst, starting from Subchannel 0. No. slot 3 The number ofslots allocated for the burst Frame 1 Indicate to start reporting at theframe. If F == 0, offset(F) the allocation applies to the UL subframetwo frames ahead of the current frame. If F == 1, for frames ahead ofthe current frame.

As depicted in Table 8, a feedback request extended subheader format canbe 3 bytes in length. If the feedback request extended subheader formatis transmitted to the MS, the MS transmits feedback informationaccording to the contents of the feedback request extended subheaderusing the allocated uplink wireless resource. In addition, an ‘OFDMAsymbol offset’ field and a ‘subchannel offset’ field provide a locationof the uplink resource for feedback information. Moreover, a ‘No. slot’field indicates a number of slots allocated for the burst or a numberslots to be used from a designated location. Here, a method of encodingfor the feedback information is determined using an Uplink IntervalUsage Code (UIUC). Lastly, a ‘frame offset’ field provides a startingframe for transmitting feedback information, where the starting frame isa frame at which the feedback information is to be begin transmitting.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A method of transmitting feedback information, the method comprising:receiving a Protocol Data Unit (PDU) which includes a Medium AccessChannel (MAC) header; determining from the MAC header whether anextended subheader group appears after the MAC header; identifying afeedback request extended subheader from the extended subheader group;and transmitting the feedback information according to the feedbackrequest extended subheader.
 2. The method of claim 1, wherein theextended subheader group appears immediately after the MAC header. 3.The method of claim 1, wherein the extended subheader group appearsbetween a subheader and a payload.
 4. The method of claim 1, wherein theexistence of the extended subheader group is indicated by an ExtendedSubheader Format (ESF) field which is included in the MAC header.
 5. Themethod of claim 4, wherein a size of the ESF field is I bit.
 6. Themethod of claim 1, wherein the extended subheader group includes anextended subheader group length, an extended subheader type, and anextended subheader body.
 7. The method of claim 6, wherein the extendedsubheader group length indicates a total length of the extendedsubheader group.
 8. The method of claim 6, wherein the extendedsubheader type indicates various types of extended subheaders.
 9. Themethod of claim 6, wherein the extended subheader body includes contentsof each extended subheader.
 10. The method of claim 9, wherein a size ofthe extended subheader body depends on the contents of the extendedsubheader.
 11. The method of claim 1, wherein the feedback requestextended subheader includes a feedback type, frame offset, subchanneloffset, an Orthogonal Frequency Division Multiplexing Access (OFDMA)symbol offset, an Uplink Interval Usage Code (UIUC), and a number ofslots.
 12. The method of claim 11, wherein the feedback type includes atleast one of downlink average carrier to interference and noise ratio(CINR) and preferred Downlink Interval Usage Code (DIUC).
 13. The methodof claim 11, wherein the frame offset indicates a starting frame fortransmitting feedback information, the starting frame is a frame atwhich the feedback information is to be transmitted.
 14. The method ofclaim 1, wherein the feedback information is transmitted via a feedbackMAC header.
 15. The method of claim 1, wherein the feedback requestextended subheader further includes an allocation type.
 16. The methodof claim 15, wherein the allocation type indicates transmitting thefeedback information using a fast-feedback channel or a feedback MACheader.
 17. The method of claim 16, wherein the feedback information istransmitted via the fast-feedback channel.
 18. A method of receivingfeedback information, the method comprising: transmitting a ProtocolData Unit (PDU) which includes a Medium Access Channel (MAC) headerwhich indicates whether an extended subheader group appears after theMAC header, wherein the extended subheader group includes a feedbackrequest extended subheader; and receiving the feedback information. 19.The method of claim 18, wherein the existence of the extended subheadergroup is indicated by an Extended Subheader Format (ESF) field which isincluded in the MAC header.
 20. The method of claim 19, wherein a sizeof the ESF field is I bit.
 21. The method of claim 18, wherein theextended subheader group includes an extended subheader group length, anextended subheader type, and an extended subheader body.
 22. The methodof claim 18, wherein the feedback request extended subheader includes afeedback type, frame offset, subchannel offset, an Orthogonal FrequencyDivision Multiplexing Access (OFDMA) symbol offset, an Uplink IntervalUsage Code (UIUC), and a number of slots.
 23. The method of claim 18,wherein the feedback information is received via a feedback MAC header.24. A system for transmitting and receiving feedback information, thesystem comprising: a base station (BS) for: transmitting a Protocol DataUnit (PDU) which includes a Medium Access Channel (MAC) header whichindicates whether an extended subheader group appears after the MACheader, wherein the extended subheader group includes a feedback requestextended subheader; and a mobile station (MS) for: receiving a ProtocolData Unit (PDU) which includes a Medium Access Channel (MAC) header,determining from the MAC header whether an extended subheader groupappears after the MAC header, identifying a feedback request extendedsubheader from the extended subheader group, and transmitting thefeedback information according to the feedback request extendedsubheader.